Lubricant



Patented Sept. 4,1945

' UNITED STATES. PATENT or ies LUBBIQAN T Alfred L. Bayes, Kenmore, N. Y. assignor to Carbide and Carbon Chemicals Corporation, a corporation-of New York No Drawing. Application June 9, 1943,

- Serial No. 490,174.

8Clalms.

conditions of use in an internal combustion engine, where oxidatiomunderhigh temperature polysulfldes, including the trisulfide, tetrasulflde 10- are not initially corrosive may become so under and pressure, usually eii'ects certain break-down in the oil, which promotes or creates corrosive conditions, as well as-other deteriorating influences. In modern automotive engines the bearing metals often are cadmium-silver, cadmium-nickel or copper-lead alloys, and these alloys are especially susceptible to corrosion in contact with mineral lubricating oils. The

problem of inhibiting the corrosive action of oils on metal surfaces, and of retarding deterioration of the oil through oxidation, is, therefore, oressential importance, and'to avoid these difliculties the addition. of inhibitors to lubrlcating oils haabecdme a common practice.

It is an object of this invention to provide new and improved oil additive materials, which are adapted in very small concentrations to impartto lubricating oil, and maintain therein,

0 substantially non-corrosive characteristics towgrd common bearing metala-while at the same t e producing in the oil a greater resistance to deterioration through oxidation. A further obor higher derivatives.

Dimorpholine monosulfide, with the sulfur linkage Z can be prepared by the reaction of morpholine and sulfur dichloride in an inert solvent such as benzene. The pure product is a white crystalline material which is soluble in most organic solvents, and has a melting point of about 112 C.

The reaction of sulfur vmonochloride with morpholine produces the sulfurlinkage I or dimorpholine disulfide. This compound is' also a white crystalline solid, containing 27.1% sulfur and having a melting point of about 123 C. A-product comprising mixtures of the polysulfide derivatives can be made by reacting morject is to provide improved mineral oil lubricants incorporating such additives.

- The inhibitor additives proposed by the invention are materials formed by mixture of two components, one a dimorpholine sulfide or polysulfide composition and the other the compound mercaptobenzothiazole. The dimorpholine derivatives which are suitable may be further described as compositions of the characteristic in which :2: represents one or more sulfur atoms.- Individual compounds of this structure, like dimorpholine monosulfideor dimorpholine disulflde are satisfactory for the purpose intended, as are also productscomprising mixtures of the pholine with elemental sulfur in the presence of lead oxide or other metal oxide catalyst; and by modification in the mol proportions of the reactants used, in the quantity and purity of the catalyst, or in the temperature of the reaction, compositions of different sulfur content can be obtained, with the sulfur varying, for example,

within the range of about 32% to 42%. The melting point of these reaction mixtures is not sharply defined, although the products usually melt within the range of C. to C., with the melting temperature decreasing as the sulfur content increases. Also with increase in sulfur content, the recovered solid products vary from white tdyellow in color.

. In the inhibitor mixture here proposed, the

dimorpholine sulfide component will .function. primarily as an anti-oxidant, and in association .with mercaptobenzothiazole a cooperative, further improved, corrosion inhibiting and antioxidant" action is attained. The latter com-v I pound is particularly effective as a, corrosion protective agent for copper-containing metals, and

it-provides in addition the joint efiect of an increased inhibitor life with regard to both antioxidant and corrosion protective. functions. Mercaptobenzothiazole alone is not readily soluble in lubricating oil, but when eaiefully and thoroughly blended with a dimorpholine sulfide component, theresulting product can be incorporated into 011 without difficulty in required inhibitiveamounts. In a preferred method of blending the two. components the mercaptobenzothiazole is dissolved in'the melted dimorpholine sulflde composition, and this fused product has advantages in the compounding with oil. There is some indication that chemical combination may occur in-such a mixture, but whether or not this is the case. the results intended by the invention can be accomplished with either a mechanically mixed or fused product. Where the additive is defined as a mixture, blending of the two components in either manner is intended.

The most effective concentrations of the new additives will vary with diflerent lubricatlng oils, and with specific lubricating conditions, but for most purposes a range of from 0.10% to 2.0% by weight of total'additive will be found satisfactory.

The individual components may be present in equal weight proportions, particularly when fused mixtures are used, but in many instancespredominating amounts of the dimorpholine sulfide will be found desirable. For example, in proportions of 0.5% of the dimorpholine sulfide, with 0.05%, 0.1% or 0.2% of mercaptobenzothiazole, excellent results have been attained, and a fused mixture of equal parts of each component, with a total additive amount of 0.2% by weight, has in some oils produced a marked inhibitor improvement.

Test results on representativeembodiments oi the invention are shown in the following table, wherein there are indicated property changes in oil, both with and-without the new additive, as

. effected by operation for 36 hours in a Chevrolet engine. A commercial Mid-Continent solvent refined oil of viscosity 8. A. E. 20 was used in these tests. The additive represented by MS is a dimorpholine polysulflde mixture, as previously described, having a sulfur content of about 39%, and MIBT is an abbreviation for mercaptobenzothiazole. simple mixture of the two components, and in the second test a fused product, in parts by weight as indicated, was used.

The protective action for hearing metals at forded by the new additives is obvious from the above results, and that oil deterioration is also ree tarded can be readily seen by the fact that the change in viscosity and neutralization number is of a substantially lower degree in the inhibited oil. The same relative results have been obtained with additive mixtures of other proportions, and

with those containing difierent morpholine derivatives within the class described. The invention contemplates usage of these new additives in any of the common petroleum lubricating oils, in-

cluding both asphaltic and paraflln base oils, and. it does not preclude the further addition of detergents, oiliness agents, or other property-modifying materials, if desired.

Ihis application contains subject matter in common with my copending application Serial No. 470,213, flied. December 26, 1942, issued as Patent No. 2,351,65'7'on June 20, 1944. Y

In one instance the additive was a 1 I claim: v

1. A lubricant comprising a mineral oil containing corromon and oxidation inhibiting amounts of an additive mixture composed of mer- 5 captobennothiazole and a dimorpholine sulfide of the structure:

o -(s),-N 0

cHrcs CHr-CKI wherein a: is at least one. 3. A lubricant comprising a mineral oil" containing corrosion and oxidation inhibiting amounts of an additive composed of ii. fused mix-,

one-cm ture of mercaptobenzothiazole and amixture of dimorpholine sulfides of the structure: CHsCHs OKs-CH:

o o one-on. cni-ci -wherein:cisatleastone andrepresentsasuliur content in the sulfide mixture of from about 32% to 42%.

38 4.A lubricant comprising a petroleum lubricating oil containing an additive-mixture composed of about 0.05% to 0.20% by weight of. mercaptobenaothiazole, and about 0.5% 0! dimorpholine sulfides of the structure:

r CHr-CH: CHE-CH: o -(s) o cni-cni Gui-chi wherein a: is at least one.

5. a lubricant comprising a petroleum lubricating oil containing about 0.2% to 1.0% .of an additive or a fused .mixture in equal parts by weight of mercaptobenzothianole and r a mixtureof dimorpholine sulfides of the structure: v /csCHs one-cg,

o s), o y one-on, cm-on,

content in the sulfide mixture of from about 32% posed of metal having the corrosion susceptibility of copper-lead and cadmium-silver alloys, which comprises applying to the bearing surfaces a'lubrlcant having incorporated therein, in

corrosion-inhibiting amountsfan additive mixture composed of mercaptobenzothiazole and a dimorpholine sulfide of the structure:

wherein isat least one.

'1. metri s of lubricating bearing surfaces composed of metal having the corrosionsusceptibillty of copper-lend and cadmium-silver alloys, which comprises applying to the bearing surfaces wherein is at least one and represents a sulfur .6. Method of lubricating bearing surfaces coma lubricant having incorporated therein an additive mixture composed of about 0.05% to 0.20% by weight of 'mer'captobenzothiazole, and about 0.5% of dimorpholine sulfide of the structure:

cam-0H on em r- 0 0 CHe-C: com-C wherein a: is at least one.

bricant incorporated therein an additive composed of a fused mixture in equal parts by weight of mercaptobenzothiazole and a mixture of dimorpholine sulfides of the structure:

cur-cm wherein a: is at least one and represents a sulfur content-in the sulfide mixture of from about 32% ALFRED 1 BAYES. 

